3 5 0 under all conditions of weather and water, for a period of five weeks cover in all more than 50,000 separate range readings. No such exhaustive' trials have ever before been undertaken in any service, and the results, as shown in the report referred to, are exceedingly gratifying, the Lewis depression finder being adopted as the standard for the Coast Artillery Service on the grounds of accuracy, simplicity of construction, ease of adjustment and operation, superiority of telescope,

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... ity and permanency of adjustment, and adap tability to change of height. The results of obser vation, according to this report, show an average error of all ranges on this instrument of 24.4 yards as against 35.1; 38.9, and 55.8 yards for the three other competing instruments. The accompanying ,photo graph shows the new model iastrument completely assembled ready for use. It consists of a 500pound cast-iron pedestal supporting a brass 20inch table and all moving parts. The masonry or concrete foundation pier, 3 feet in diameter, is sufficient to hold the instrument accurately in azimuth adjustment. The range scale reads from 1,500 to 12,000 yards, and it is properly co' rrected for effects of earth curvature and normal at mospheric refraction, while an easily-applied thumb screw connection is provided to compen sate for eff ects of abnormal refraction.